[MM-62408] Server Code Coverage with Fully Parallel Tests (#30078)

* TestPool

* Store infra

* Store tests updates

* Bump maximum concurrent postgres connections

* More infra

* channels/jobs

* channels/app

* channels/api4

* Protect i18n from concurrent access

* Replace some use of os.Setenv

* Remove debug

* Lint fixes

* Fix more linting

* Fix test

* Remove use of Setenv in drafts tests

* Fix flaky TestWebHubCloseConnOnDBFail

* Fix merge

* [MM-62408] Add CI job to generate test coverage (#30284)

* Add CI job to generate test coverage

* Remove use of Setenv in drafts tests

* Fix flaky TestWebHubCloseConnOnDBFail

* Fix more Setenv usage

* Fix more potential flakyness

* Remove parallelism from flaky test

* Remove conflicting env var

* Fix

* Disable parallelism

* Test atomic covermode

* Disable parallelism

* Enable parallelism

* Add upload coverage step

* Fix codecov.yml

* Add codecov.yml

* Remove redundant workspace field

* Add Parallel() util methods and refactor

* Fix formatting

* More formatting fixes

* Fix reporting

server/channels/app/email/email_batching_test.go

@@ -16,6 +16,8 @@ import (
 )
 
 func TestHandleNewNotifications(t *testing.T) {
+	mainHelper.Parallel(t)
+
 	th := SetupWithStoreMock(t)
 	defer th.TearDown()
 
@@ -75,6 +77,7 @@ func TestHandleNewNotifications(t *testing.T) {
 }
 
 func TestCheckPendingNotifications(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 
@@ -194,6 +197,7 @@ func TestCheckPendingNotifications(t *testing.T) {
  * Ensures that email batch interval defaults to 15 minutes for users that haven't explicitly set this preference
  */
 func TestCheckPendingNotificationsDefaultInterval(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 
@@ -237,6 +241,7 @@ func TestCheckPendingNotificationsDefaultInterval(t *testing.T) {
  * Ensures that email batch interval defaults to 15 minutes if user preference is invalid
  */
 func TestCheckPendingNotificationsCantParseInterval(t *testing.T) {
+	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()
 	defer th.TearDown()